429 lines
11 KiB
Perl
429 lines
11 KiB
Perl
package ExtUtils::Constant;
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use vars qw (@ISA $VERSION @EXPORT_OK %EXPORT_TAGS);
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$VERSION = 0.20;
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=head1 NAME
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ExtUtils::Constant - generate XS code to import C header constants
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=head1 SYNOPSIS
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use ExtUtils::Constant qw (WriteConstants);
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WriteConstants(
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NAME => 'Foo',
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NAMES => [qw(FOO BAR BAZ)],
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);
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# Generates wrapper code to make the values of the constants FOO BAR BAZ
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# available to perl
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=head1 DESCRIPTION
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ExtUtils::Constant facilitates generating C and XS wrapper code to allow
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perl modules to export constants defined in C library header files.
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It is principally used by the C<h2xs> utility, on which this code is based.
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It doesn't contain the routines to scan header files to extract these
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constants.
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=head1 USAGE
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Generally one only needs to call the C<WriteConstants> function, and then
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#include "const-c.inc"
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in the C section of C<Foo.xs>
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INCLUDE: const-xs.inc
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in the XS section of C<Foo.xs>.
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For greater flexibility use C<constant_types()>, C<C_constant> and
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C<XS_constant>, with which C<WriteConstants> is implemented.
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Currently this module understands the following types. h2xs may only know
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a subset. The sizes of the numeric types are chosen by the C<Configure>
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script at compile time.
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=over 4
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=item IV
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signed integer, at least 32 bits.
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=item UV
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unsigned integer, the same size as I<IV>
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=item NV
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floating point type, probably C<double>, possibly C<long double>
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=item PV
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NUL terminated string, length will be determined with C<strlen>
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=item PVN
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A fixed length thing, given as a [pointer, length] pair. If you know the
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length of a string at compile time you may use this instead of I<PV>
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=item SV
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A B<mortal> SV.
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=item YES
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Truth. (C<PL_sv_yes>) The value is not needed (and ignored).
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=item NO
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Defined Falsehood. (C<PL_sv_no>) The value is not needed (and ignored).
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=item UNDEF
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C<undef>. The value of the macro is not needed.
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=back
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=head1 FUNCTIONS
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=over 4
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=cut
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use warnings;
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use strict;
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use Exporter;
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use ExtUtils::Constant::Utils qw(C_stringify);
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use ExtUtils::Constant::XS qw(%XS_Constant %XS_TypeSet);
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@ISA = 'Exporter';
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%EXPORT_TAGS = ( 'all' => \@( qw(
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XS_constant constant_types C_stringify
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C_constant WriteConstants WriteMakefileSnippet
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) ) );
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@EXPORT_OK = ( @{ %EXPORT_TAGS{'all'} } );
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=item constant_types
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A function returning a single scalar with C<#define> definitions for the
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constants used internally between the generated C and XS functions.
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=cut
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sub constant_types {
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ExtUtils::Constant::XS->header();
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}
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sub C_constant {
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my ($package, $subname, $default_type, $what, $indent, $breakout, @items)
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= @_;
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ExtUtils::Constant::XS->C_constant(\%(package => $package, subname => $subname,
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default_type => $default_type,
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types => $what, indent => $indent,
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breakout => $breakout), @items);
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}
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=item XS_constant PACKAGE, TYPES, SUBNAME, C_SUBNAME
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A function to generate the XS code to implement the perl subroutine
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I<PACKAGE>::constant used by I<PACKAGE>::AUTOLOAD to load constants.
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This XS code is a wrapper around a C subroutine usually generated by
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C<C_constant>, and usually named C<constant>.
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I<TYPES> should be given either as a comma separated list of types that the
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C subroutine C<constant> will generate or as a reference to a hash. It should
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be the same list of types as C<C_constant> was given.
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[Otherwise C<XS_constant> and C<C_constant> may have different ideas about
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the number of parameters passed to the C function C<constant>]
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You can call the perl visible subroutine something other than C<constant> if
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you give the parameter I<SUBNAME>. The C subroutine it calls defaults to
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the name of the perl visible subroutine, unless you give the parameter
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I<C_SUBNAME>.
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=cut
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sub XS_constant {
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my $package = shift;
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my $what = shift;
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my $subname = shift;
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my $C_subname = shift;
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$subname ||= 'constant';
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$C_subname ||= $subname;
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if (!ref $what) {
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# Convert line of the form IV,UV,NV to hash
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$what = \%( map {$_ => 1} split m/,\s*/, ($what) );
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}
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my $params = ExtUtils::Constant::XS->params ($what);
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my $type;
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my $xs = <<"EOT";
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void
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$subname(sv)
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PREINIT:
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#ifdef dXSTARG
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dXSTARG; /* Faster if we have it. */
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#else
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dTARGET;
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#endif
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STRLEN len;
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int type;
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EOT
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if ($params->{IV}) {
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$xs .= " IV iv;\n";
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} else {
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$xs .= " /* IV\t\tiv;\tUncomment this if you need to return IVs */\n";
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}
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if ($params->{NV}) {
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$xs .= " NV nv;\n";
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} else {
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$xs .= " /* NV\t\tnv;\tUncomment this if you need to return NVs */\n";
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}
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if ($params->{PV}) {
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$xs .= " const char *pv;\n";
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} else {
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$xs .=
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" /* const char\t*pv;\tUncomment this if you need to return PVs */\n";
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}
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$xs .= << 'EOT';
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INPUT:
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SV * sv;
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const char * s = SvPV(sv, len);
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EOT
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$xs .= << 'EOT';
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PPCODE:
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EOT
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if ($params->{IV} xor $params->{NV}) {
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$xs .= << "EOT";
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/* Change this to $C_subname(aTHX_ s, len, &iv, &nv);
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if you need to return both NVs and IVs */
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EOT
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}
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$xs .= " type = $C_subname(aTHX_ s, len";
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$xs .= ', &iv' if $params->{IV};
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$xs .= ', &nv' if $params->{NV};
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$xs .= ', &pv' if $params->{PV};
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$xs .= ', &sv' if $params->{SV};
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$xs .= ");\n";
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# If anyone is insane enough to suggest a package name containing %
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my $package_sprintf_safe = $package;
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$package_sprintf_safe =~ s/%/\%\%/g;
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$xs .= << "EOT";
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/* Return 1 or 2 items. First is error message, or undef if no error.
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Second, if present, is found value */
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switch (type) \{
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case PERL_constant_NOTFOUND:
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sv =
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sv_2mortal(newSVpvf("\%s is not a valid $package_sprintf_safe macro", s));
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PUSHs(sv);
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break;
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case PERL_constant_NOTDEF:
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sv = sv_2mortal(newSVpvf(
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"Your vendor has not defined $package_sprintf_safe macro \%s, used",
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s));
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PUSHs(sv);
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break;
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EOT
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foreach $type (sort keys %XS_Constant) {
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# '' marks utf8 flag needed.
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next if $type eq '';
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$xs .= "\t/* Uncomment this if you need to return {$type}s\n"
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unless $what->{$type};
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$xs .= " case PERL_constant_IS$type:\n";
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if (length %XS_Constant{$type}) {
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$xs .= << "EOT";
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EXTEND(SP, 1);
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PUSHs(&PL_sv_undef);
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%XS_Constant{$type};
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EOT
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} else {
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# Do nothing. return (), which will be correctly interpreted as
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# (undef, undef)
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}
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$xs .= " break;\n";
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unless ($what->{$type}) {
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chop $xs; # Yes, another need for chop not chomp.
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$xs .= " */\n";
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}
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}
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$xs .= << "EOT";
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default:
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sv = sv_2mortal(newSVpvf(
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"Unexpected return type \%d while processing $package_sprintf_safe macro \%s, used",
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type, s));
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PUSHs(sv);
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\}
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EOT
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return $xs;
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}
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=item WriteMakefileSnippet
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WriteMakefileSnippet ATTRIBUTE =E<gt> VALUE [, ...]
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A function to generate perl code for Makefile.PL that will regenerate
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the constant subroutines. Parameters are named as passed to C<WriteConstants>,
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with the addition of C<INDENT> to specify the number of leading spaces
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(default 2).
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Currently only C<INDENT>, C<NAME>, C<DEFAULT_TYPE>, C<NAMES>, C<C_FILE> and
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C<XS_FILE> are recognised.
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=cut
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sub WriteMakefileSnippet {
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my %args = @_;
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my $indent = %args{INDENT} || 2;
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my $result = <<"EOT";
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ExtUtils::Constant::WriteConstants(
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NAME => '%args{NAME}',
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NAMES => \\\@names,
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DEFAULT_TYPE => '%args{DEFAULT_TYPE}',
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PROXYSUBS => 1,
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EOT
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foreach (qw (C_FILE XS_FILE)) {
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next unless exists %args{$_};
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$result .= sprintf " \%-12s => '\%s',\n",
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$_, %args{$_};
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}
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$result .= <<'EOT';
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);
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EOT
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$result =~ s/^/{' 'x$indent}/gm;
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return ExtUtils::Constant::XS->dump_names(\%(default_type=>%args{DEFAULT_TYPE},
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indent=>$indent,),
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@{%args{NAMES}})
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. $result;
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}
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=item WriteConstants ATTRIBUTE =E<gt> VALUE [, ...]
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Writes a file of C code and a file of XS code which you should C<#include>
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and C<INCLUDE> in the C and XS sections respectively of your module's XS
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code. You probably want to do this in your C<Makefile.PL>, so that you can
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easily edit the list of constants without touching the rest of your module.
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The attributes supported are
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=over 4
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=item NAME
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Name of the module. This must be specified
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=item DEFAULT_TYPE
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The default type for the constants. If not specified C<IV> is assumed.
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=item BREAKOUT_AT
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The names of the constants are grouped by length. Generate child subroutines
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for each group with this number or more names in.
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=item NAMES
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An array of constants' names, either scalars containing names, or hashrefs
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as detailed in L<"C_constant">.
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=item C_FH
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A filehandle to write the C code to. If not given, then I<C_FILE> is opened
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for writing.
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=item C_FILE
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The name of the file to write containing the C code. The default is
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C<const-c.inc>. The C<-> in the name ensures that the file can't be
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mistaken for anything related to a legitimate perl package name, and
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not naming the file C<.c> avoids having to override Makefile.PL's
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C<.xs> to C<.c> rules.
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=item XS_FH
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A filehandle to write the XS code to. If not given, then I<XS_FILE> is opened
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for writing.
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=item XS_FILE
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The name of the file to write containing the XS code. The default is
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C<const-xs.inc>.
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=item SUBNAME
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The perl visible name of the XS subroutine generated which will return the
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constants. The default is C<constant>.
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=item C_SUBNAME
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The name of the C subroutine generated which will return the constants.
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The default is I<SUBNAME>. Child subroutines have C<_> and the name
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length appended, so constants with 10 character names would be in
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C<constant_10> with the default I<XS_SUBNAME>.
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=back
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=cut
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sub WriteConstants {
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my %ARGS =
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( # defaults
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C_FILE => 'const-c.inc',
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XS_FILE => 'const-xs.inc',
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SUBNAME => 'constant',
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DEFAULT_TYPE => 'IV',
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@_);
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%ARGS{C_SUBNAME} ||= %ARGS{SUBNAME}; # No-one sane will have C_SUBNAME eq '0'
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die "Module name not specified" unless length %ARGS{NAME};
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my $c_fh = %ARGS{C_FH};
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if (!$c_fh) {
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open $c_fh, ">", "%ARGS{C_FILE}" or die "Can't open %ARGS{C_FILE}: $!";
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}
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my $xs_fh = %ARGS{XS_FH};
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if (!$xs_fh) {
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open $xs_fh, ">", "%ARGS{XS_FILE}" or die "Can't open %ARGS{XS_FILE}: $!";
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}
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# As this subroutine is intended to make code that isn't edited, there's no
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# need for the user to specify any types that aren't found in the list of
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# names.
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if (%ARGS{PROXYSUBS}) {
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require ExtUtils::Constant::ProxySubs;
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%ARGS{C_FH} = $c_fh;
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%ARGS{XS_FH} = $xs_fh;
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ExtUtils::Constant::ProxySubs->WriteConstants(%ARGS);
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} else {
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die "Ony ProxySubs are supported";
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}
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close $c_fh or warn "Error closing %ARGS{C_FILE}: $!" unless %ARGS{C_FH};
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close $xs_fh or warn "Error closing %ARGS{XS_FILE}: $!" unless %ARGS{XS_FH};
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}
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1;
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__END__
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=back
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=head1 AUTHOR
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Nicholas Clark <nick@ccl4.org> based on the code in C<h2xs> by Larry Wall and
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others
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=cut
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